An electric motor often includes a protector capable of shutting down the motor before it is damaged due to an abnormality such as excessive heat. A typical protector is electrically connected to the winding and is adapted to break the current through the winding when the protector senses excessive temperature and/or current in the winding.
Protectors may be “on-winding” protectors, which are mounted directly on the windings, or “off-winding” protectors, which are mounted in a position remote from the windings. It is often beneficial to use on-winding protectors so that the thermal sensor is more responsive to changes in temperature in the windings. By measuring the temperature at the windings, e.g., without a significant gap between the windings and the sensor, the protector can respond more quickly to break current when the windings overheat.
A major disadvantage of many on-winding protectors is simply the added cost. For example, the on-winding protectors are more expensive because they must be more robust to withstand the stress of being mounted on the windings. On-winding protectors are typically formed with housings that are rigid enough to allow the protector to be “strapped” to the windings, e.g., the protector is fastened to the windings by lacing or straps. The robust housing of the on-winding protector is designed to prevent the lacing from bending or otherwise damaging the sensor or sensors inside the housing. In contrast, off-winding protectors are not as robust, and can therefore be made significantly cheaper than on-winding protectors.
Accordingly, it is known in the prior art to mount on-winding protectors directly on the windings using lacing or straps over the protector. It is also known to alter the pattern of lacing or straps (referred to in the lacing art as “controlling the dwell of the lacing”) so that they do not extend directly over the on-winding protector. However, the prior art solutions fail to create an economical apparatus for mounting a cheaper, off-winding protector directly on the windings.